Unit 2 - Module 9: The Neuron and Neural Communication

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Grade 12 Psychology (Unit Two - Biological Bases of Behaviour) Flashcards on Unit 2 - Module 9: The Neuron and Neural Communication, created by Greg MacPherson on 09/21/2021.
Greg MacPherson
Flashcards by Greg MacPherson, updated 8 days ago
Greg MacPherson
Created by Greg MacPherson almost 3 years ago
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Unit Two - Module 9 The Neuron and Neural Communication The Neuron and Neural Communication
neuron A neuron is a nerve cell that is the basic building block of the nervous system. Neurons are similar to other cells in the human body in a number of ways, but there is one key difference - neurons are specialized to transmit information throughout the body.
cell body (soma) The part of the neuron that contains the nucleus - the life support centre of the cell.
dendrites The bushy branching extensions of a neuron that receive and integrate messages and then conduct impulses toward the cell body.
axon The neuron extension that conducts neural impulses to other neurons or muscle or gland cells.
terminal branches (buttons) The terminal branches (buttons) are located at the end of the neuron and are responsible for sending the signal on to other neurons (or muscles or glands). At the end of the terminal button is a gap known as a synapse.
myelin sheath The insulating layer around many axons that increases the speed of conduction of nerve impulses. The myelin sheath is interrupted by small gaps, called nodes of Ranvier, which are spaced about every millimeter along the axon.
nodes of Ranvier Regularly spaced gaps in the myelin sheath surrounding an axon. The gaps permit the exchange of ions across the plasma membrane at those points, allowing the nerve impulse to leap from one node to the next in so-called saltatory conduction along the axon.
glial cell (neuroglia) Non-neuronal tissue in the nervous system that provides structural, nutritional, and other kinds of support to neurons.
oligodendroglia Oligodendrocytes are a type of glial cells that form myelin sheath on neurons in the central nervous system and Schwann cells in the peripheral nervous system.
Schwann cells Schwann cells are a type of glial cells that form myelin sheath on neurons in the peripheral nervous system.
astrocytes Astrocytes are star-shaped glial cells and form the matrix in which neural cells are embedded. They also absorb dead neural cells.
action potential The change in electric potential along the axon of a neuron during the transmission of a nerve impulse It is marked by a rapid depolarization of the cell’s plasma membrane, from a resting potential of about –70 mV (inside negative) to about +40 mV (inside positive), and back again, after a slight hyperpolarization, to the resting potential. Each action potential takes just a few milliseconds.
resting membrane potential The electric potential across the plasma membrane of a neuron when it is in the nonexcited, or resting, state. It is usually in the range of -70mV representing an excess of negatively charged ions on the inside of the membrane.
sodium-potassium pump This pump is embedded in the membrane and maintains the resting membrane potential. This means that it keeps pumping more sodium ions (Na+) out of the neuron and fewer potassium ions (K+) into the neuron This keeps the inside of the neuron more negative which keeps the resting potential of -70mV.
selective permeability The membrane of the axon is selectively permeable, which means that it has channels or "gates" that only allow certain ions to cross the membrane and only at certain times.
all-or-none response The all-or-none law is a principle that states that the strength of a response of a nerve cell is not dependent upon the strength of the stimulus. Essentially, there will either be a full response or there will be no response at all for an individual neuron.
depolarization A reduction in the electric potential across the membrane of neuron, such that the inner surface of the membrane becomes less negative in relation to the outer surface. Depolarization occurs when the membrane is stimulated and sodium ions (Na+) flow into the cell. If the stimulus intensity exceeds the excitatory threshold of the neuron, an action potential is created and a nerve impulse propagated.
threshold Threshold is the minimum stimulus intensity that triggers an action potential in a neuron. it is usually -55mV.
repolarization The change in membrane potential that returns it to a negative value just after the depolarization phase of an action potential.
hyperpolarization Repolarization always leads first to hyperpolarization, a state in which the membrane potential is more negative than the default membrane potential.For example, it might go to -100mV before returning to -70mV.
refractory period This is the period after an action potential has been generated but before the next one can be generated. The next action potential in a neuron cannot be generated until the membrane has returned to normal. This refractory period is to ensure that the signal only travels in one direction.
synapse The specialized junction through which neural signals are transmitted from one neuron (the presynaptic neuron) to another (the postsynaptic neuron). In most synapses, the terminal button of the axon of a presynaptic neuron faces the dendrite or cell body of the postsynaptic neuron across a narrow gap, the synaptic cleft.
synaptic gap (cleft) The gap within a synapse between the terminal button ending of the axon of one neuron and the dendrite or cell body of a neighboring neuron. The synaptic cleft is typically 20 to 30 nm wide. Also called synaptic gap.
synaptic vesicles Numerous small spherical sacs in the terminal button ending of the axon of a presynaptic neuron that contain molecules of neurotransmitter. The transmitter is released into the synaptic cleft when a nerve impulse arrives at the terminal button.
reuptake The process by which neurotransmitter molecules that have been released at a synapse are reabsorbed by the presynaptic neuron that released them.
excitation The binding of a neurotransmitter to a receptor site produces a chemical reaction that depolarizes (excites) the cell membrane. If threshold is reached, an action potential is created and an impulse is sent down the neuron.
inhibition The binding of a neurotransmitter to a receptor site produces a chemical reaction that will hyperpolarize the membrane. This will make it more difficult for the neuron to be excited and reach threshold and therefore inhibits its function.
neurotransmitters Chemicals that are released by neurons to mediate transmission of nerve signals across the junctions (synapses) between neurons. When triggered by a nerve impulse, the neurotransmitter is released from the terminal button, travels across the synaptic cleft, and binds to and reacts with receptor molecules in the postsynaptic membrane.
acetylcholine (ACh) Neurotransmitter that enables muscle contraction, learning and memory.
dopamine Neurotransmitter that influences learning movement, attention, and emotion.
serotonin Neurotransmitter that affects mood, hunger, sleep, and arousal.
endorphins Neurotransmitters that influence the perception of pain and pleasure.
Substance P Neurotransmitter involved in pain percpetion and immune response.
agonist A drug or chemical that increases the activity of a neurotransmitter.
antagonist A drug or chemical that inhibits or decreases the activity of a neurotransmitter.
reuptake inhibitor A drug or chemical that stops the reuptake of a neurotransmitter into the presynaptic axon terminal. This leaves more of the neurotransmitter in the synapse, creating an enhanced effect of that neurotransmitter.
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